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Takes an object of class mids, fills in the missing data, and returns the completed data in a specified format.


# S3 method for mids
  action = 1L,
  include = FALSE,
  mild = FALSE,
  order = c("last", "first"),



An object of class mids as created by the function mice().


A numeric vector or a keyword. Numeric values between 1 and data$m return the data with imputation number action filled in. The value of action = 0 return the original data, with missing values. action can also be one of the following keywords: "all", "long", "broad" and "repeated". See the Details section for the interpretation. The default is action = 1L returns the first imputed data set.


A logical to indicate whether the original data with the missing values should be included.


A logical indicating whether the return value should always be an object of class mild. Setting mild = TRUE overrides action keywords "long", "broad" and "repeated". The default is FALSE.


Either "first" or "last". Only relevant when action == "long". Writes the ".imp" and ".id" in columns 1 and 2. The default is order = "last". Included for backward compatibility with "< mice 3.16.0".


Additional arguments. Not used.


Complete data set with missing values replaced by imputations. A data.frame, or a list of data frames of class mild.


The argument action can be length-1 character, which is matched to one of the following keywords:


produces a mild object of imputed data sets. When include = TRUE, then the original data are appended as the first list element;


produces a data set where imputed data sets are stacked vertically. The columns are added: 1) .imp, integer, referring the imputation number, and 2) .id, character, the row names of data$data;


same as "long" but without the two additional columns;


produces a data set with where imputed data sets are stacked horizontally. Columns are ordered as in the original data. The imputation number is appended to each column name;


same as "broad", but with columns in a different order.


Technical note: mice 3.7.5 renamed the complete() function to complete.mids() and exported it as an S3 method of the generic tidyr::complete(). Name clashes between mice::complete() and tidyr::complete() should no longer occur.

See also


# obtain first imputed data set
#> [1] 27
imp <- mice(nhanes2, print = FALSE, maxit = 1)
dat <- complete(imp)
#> [1] 0

# obtain stacked third and fifth imputation
dat <- complete(imp, c(3, 5))

# obtain all datasets, with additional identifiers
head(complete(imp, "long"))
#>     age  bmi hyp chl .imp .id
#> 1 20-39 30.1  no 229    1   1
#> 2 40-59 22.7  no 187    1   2
#> 3 20-39 33.2  no 187    1   3
#> 4 60-99 21.7  no 284    1   4
#> 5 20-39 20.4  no 113    1   5
#> 6 60-99 21.7  no 184    1   6

# same, but now as list, mild object
dslist <- complete(imp, "all")
#> [1] 5

# same, but also include the original data
dslist <- complete(imp, "all", include = TRUE)
#> [1] 6

# select original + 3 + 5, store as mild
dslist <- complete(imp, c(0, 3, 5), mild = TRUE)
#> [1] "0" "3" "5"